Extraction of iodine from aqueous iodide solutions using anion exchange resins is known. Jap. 52/4464 describes such a process in which underground brine water containing iodide is acidified with H.sub.2 SO.sub.4 and chlorinated to liberate iodine. The oxidized brine is passed through a strongly basic anion exchange resin which adsorbs the iodine. Iodine is eluted from the resin with an aqueous caustic sodium sulfite solution. Iodine is recovered from the eluate by acidification and oxidation with chlorine. Residual iodide is eluted from the resin using an aqueous alkali chloride or sulfate.
Jap. 52/1511 describes another suitable method in which brine containing iodide is passed through a highly basic anion exchange resin in chloride form to adsorb iodide. Following this, the iodide is oxidized on the resin to iodine by passing aqueous ferric chloride or hydrogen peroxide through the resin. This procedure is repeated many times until the
Jap. 59/9258 describes a process in which alkaline brine is aerated to adjust pH to 7-9 and then oxidized with chlorine to liberate iodine. The oxidized brine is then passed through a strongly basic anion exchange resin to adsorb iodine.
Jap. 70/31842 describes a process in which chlorine water is added to alkaline brine containing iodide ion and the resulting solution passed through a strongly basic anion exchange resin to adsorb iodine and iodide.
Nakamura et al, U.S. 3,346,331, describe the adsorption of iodine on an anion exchange resin by chlorinating a portion of natural gas well water containing iodide and alternating passage of chlorinated and unchlorinated well water through the anion exchange resin to load the resin with iodine.